Spectroscopic analysis or spectroscopy pertains to the study of the dispersion of light into its component wavelengths. By analyzing the absorption and dispersion of incident light and other radiation by matter, scientists are able to study various properties of the matter such as temperature, mass, luminosity, composition, etc. Optical instruments known as spectrometers are used to measure and study such light dispersion. Spectrometers therefore play an essential role in the study and design of various scientific monitoring devices, for example multi-spectral imaging (MSI) systems, hyper-spectral imaging (HSI) systems, and the like.
In a conventional spectrometer, incident light passes through a first linear opening or slit in a mirror or an optical lens. A beam of incident light passing through the first slit illuminates a prism or a linear grating device. The grating device may have a series of vertically-aligned gratings which diffract the incident light into its component colors, with each color corresponding to a particular band of wavelengths of the electromagnetic spectrum.
Spectrometers may include multiple aperture slits, with the first slit positioned in front of the linear grating device to initially select light in a relatively narrow band of wavelengths. The linear grating device spreads this portion of the light beam at different wavelength-dependent angles. A second slit in another mirror or optical lens may be positioned to allow selective passage of a narrower band of the light beam from the linear grating device. The second slit may be used to direct selected wavelengths to a measurement device to determine a desired spectral characteristic. In this manner, a specific wavelength or set of wavelengths may be selected for detailed spectral analysis.
Conventional spectrometers as described above are often used to acquire and analyze light from a single point source, but may require additional lenses or mirrors to capture a point light source. Because a single spectrometer cannot make a two-dimensional (2D) image without scanning, the total speed of acquiring 2D spectral data is also relatively slow. For example, if it takes approximately 10 seconds to resolve a first spot, 1024×768 images will require 7,864,320 seconds or 91 days to complete. A multi-channel position-sensitive device or Charged Coupled Detector (CCD) array may eliminate the need for a linear aperture slit, but nevertheless may require the additional dimension in order to function properly. A red-green-blue (RGB) CCD array may be used to capture 2D images. However, the color filters of such CCD arrays may have less than optimal spectral resolution.